Hydraulic brake for railway or tramway vehicles.



N0. 667,8l9. Patented Feb. l2, l90l. C. DUBEY.

HYDRAULIC BRAKE FUR RAILWAY OR'TBAMWAY VEHICLES.

. (Application filed July 10, 1900.)

(No Model.)

INVENTOR Arm/m r3 ms PEYER! co. wow-urns" WASHINGTON c lUNiTE SnaresATENT FFICE.

CAMILLE DUREY, OF PARIS, FRANCE, ASSIGNOR TO THE COMPAGNIEINTERNATIONALE DU FREIN ELEOTRO-HYDRAULIQUE DUREY, OF

BRUSSELS, BELGIUM.

HYDRAULlC BRAKE FOR RAILWAY OR TRAIVIWAY VEHICLES.

SPECIFICATION forming part of Letters Patent N 0. 667,819, datedFebruary 12, 1901.

Application filed July 10, 1900- Serial No. 23,085. (No model.) I

To on whom it may concern:

Be it known that I, CAMILLE DUREY, of Paris, France, have inventedcertain new and useful Improvements in Hydraulic Brakes for Railway orTramway Vehicles, of which the following is a full, clear, and exactdescription.

The present invention has for its object certain improvements in thehydraulic brake described in my Patent No. 659,517, dated October 9,1900. These improvements relate more particularly to the apparatus foroperating the brake.

The operating apparatus hereinafter described, and which is moreparticularly intended for separate automobile vehicles, allows of thebrake being taken off or applied fully or of a moderatepredeterminedbraking being maintained on the tires of the wheels by means of a singlelever operating a cam which works in a chamber in constant communicationwith the open air-reservoir. As may be easily seen, this simple means ofoperating has not only the advantage of dispensing with all kinds oftaps under pressure and the leakages due to such taps, but it alsoallows of an easy change from a hard or strong application of the braketo the 86am quo with a moderate application of the brake without itsbeing necessary to pass through the intermediate position of an unbrakedcondition.

The invention is shown in detail in the accompanying drawings, in which-Figure 1 is a longitudinal section of the whole of the brake, showingthe parts of the operating mechanism in position for applying the brake.Fig. 2 is a sectional side elevation in detail, showing the lever andthe operating-cam in the position in which the brake is applied. Fig. 3is a section of adetail of the operating apparatus, the parts being in aposition of stem quo; and Fig. 4 is a similar section showing the partsin the position of applying and taking off the brake.

The brake is composed of the following parts: a pump 1, single-acting asregards suction and double-acting when forcing, such as described inapplication Serial No. 736,417, of 1899, set in movement by an eccentric2, mounted on the axle of the vehicle, a brakecylinder 3,liquid-reservoir 4:, and special chest 5, having superimposed valves,which will be hereinafter described. A pipe 17 connects the reservoirwith the rear of the brakecylinder.

The chest 5 comprises four superimposed chambers 6, 7, S, and 9,separated by partitions 10 11 12, which serve as seats, respectively,for three winged valves a b c, the axes of which are thus in the samevertical line. The operating-lever Z, on which a cam d is keyed,penetrates through a stuffing-box into the chamber 6, which communicatesby a pipe 13 with the reservoir 4, open to the air. The chamber 7communicates directly or by means of a pipe 14 with the rear face of thepistonf of the pump 1, and the chamber 8 communicates by a pipe 15 withan annular space 9 inclosed between the piston-rod f and the body of thepump. Finally, the chamber 9 communicates by a pipe 16 with the brakecylinder.

A piston p, guided between the walls of the chest, bears constantly withits lower face upon a cam d, while an upper projection on said pistonbears against the lower valve a. The cam cl is situated in the plane ofthe vertical axis of the three valves, and its shape is such that whenthe lever Z is given successively the positions I, II, and III,(indicated in Fig. 1,) first, the three valves can move freely and fallback on their seats, Fig. 1; secondly, the valves Cb and b are keptraised, while the valve 0 is free and can fall back on its seat, Fig.3,and, thirdly, the three valves a, l), and c are kept raised from theirseats.

Now supposing the piston f to be at the end of its course. In itsdisplacement from left to right it will draw liquid from the reservoir 4through the valve a. The size of the pistonrod is arranged so that thecross-sectional area of the annular space or area g remaining aroundthis rod shall be half the area of a section of the pump-cylinder. Whenthe piston f returns from left to right, it forces behind it the liquidaccumulated. Half this liquid passes through the valves 17 and c inorder to reach the brake-cylinder 3 through the pipe 16, While the otherhalf of the liquid occupies the space communicating with the right-handface of the piston and comprising the chamber 8, pipe 15, and space g.The piston f again moving toward the right, the liquid accumulated in gpasses into the brakecylinder through the valve 0. Thus when the lever Zis in its position I, which corresponds to the application of the brake,the pump produces a continuous movement of liquid in the pipe 16. Theliquid coming into the cylinder 3 drives before it the entirebrakepiston until the brake-shoes are in contact with the wheels. Atthis moment the movement of the head 2' of the piston is stopped, and onthe liquid continuing to flow into the space h the part 71. continuesits movement,

pressing in front of it the spring T, which' transmits its pressure tothe head i, and consequent-1y to the brake-shoes through thebrake-gearing. The pressure continues to increase until the wheels arefully braked.

In order to avoid skidding from full braking while giving the brake itsmaximum power, I have designed the following arrangement: A red m isformed part of or attached to the head 11 and becomes stationary whenthe brake-shoes are in contact with the wheels, the length of said rod mbeing so arranged that when skidding is approaching, on the partcontinuing its movementtoward the right the valve 3, located in saidpart, will encounter said rod, and is thereby opened, allowing theexcess of liquid under pressure to escape.

If, instead of desiring to stop the vehicle, it is simply desired thatits speed should be diminished, the lever Zis brought into the positionIIthat is to say, the position of 5mm quo--Fig. 3. The cam d then liftsthe two valves a and b, and the pump works without effect-that is tosay, it returns to the reservoir the liquid which it draws up, the valve0 remaining pressed on its seat, and the liquid under pressure remainsstored up in the brake. If it be desired to further apply the brake, thecam is brought back into the position corresponding to the position I,(braklever Z, which actuates the cam d, the pres-' sure may be increasedor diminished to the extent desired. It will be noticed that thisarrangement for operating by means of a cam acting directly on threesuperimposed valves for the suction and forcing by the pump and formaintaining the position of-the piston of the brake-cylinder reduces toa minimum the power required for operating the brake. All taps aredispensed with. The cam d is in a chamber where the liquid is at theatmospheric pressure, and there is no internal pressure, andconsequently no cause for leakage.

I declare that what I claim is In a hydraulic brake for railway andtramway vehicles an apparatus for operating the brake consisting of adistributing-chest hav ing four superimposed chambers 6, 7, 8 and 9separated by three valves a, I) and c the axes of which are arrangedvertically one above another, and an operating device (such as a cam d)moving in the lower chamber 6 adapted to lift successively orsimultaneously the two lower valves or all three valves, the saidchambers 6,7, 8 and 9 communicating respectively with an openair-reservoir, the rear face of the pump-piston, the front face of thesame piston and the brake-cylinder, substantially as hereinbefore setforth.

In witness whereof I have hereunto set my hand in presence of twowitnesses.

CAMILLE DUREY.

\Vitnesses:

ANDRE MOSTICKER, EDWARD P. MAOLEAN.

